posted on 2021-12-22, 13:34authored byBaoai Fu, Alan J. McCue, Yanan Liu, Shaoxia Weng, Yuanfei Song, Yufei He, Junting Feng, Dianqing Li
A strategy
to fabricate a stable and site-isolated Ni catalyst
is reported. Specifically, Mo3S4 clusters allowed
individual Ni atoms to bond with Mo and S to create a type of active
site. A site-isolated Ni1MoS/Al2O3 sample exhibited high performance in the selective hydrogenation
of acetylene. Concretely, 90% ethylene selectivity was achievable
at full acetylene conversion under relatively mild reaction conditions
without any obvious decay in performance observed during longer testing
periods. In contrast, a reference catalyst with Ni ensembles exhibited
poor selectivity and stability. Density functional theory (DFT) calculations
suggested that H2 molecules were activated by a heterolytic
route over Ni1MoS/Al2O3, which enhanced
the reaction rate. Improved selectivity originated from the unique
isolated Niδ+ structure induced by Mo and S, which
facilitated product desorption as opposed to overhydrogenation or
oligomerization. This work provides a feasible way to construct site-isolated
catalysts with higher active metal loadings and opens up an opportunity
for selective hydrogenation.